its D) C2B (consumer to business) which allows consumers to name their own price for products and services
C2B model, also called a reverse auction or demand collection model, enables buyers to name or demand their own price, which is often binding, for a specific good or service. The website collects the demand bids then offers the bids to participating sellers.
C2C, or customer-to-customer, or consumer-to-consumer, is a business model that facilitates the transaction of products or services between customers. It is one of four categories of e-commerce, along with B2B (business to business), C2B (customer to business) and B2C (business to customer)
B2B and B2G has nothing to concern about consumer price setting